Method of preventing or lessening the formation of longitudinal stripes in looped fabrics and mechanism for carrying out that method



Get. '22. 1940. 5 2,218,696

. CHELLER METHOD OF PREV ING 0R LESSENING THE FORMATION AND OFLONGITUDINAL STRIPES IN LOOPED FABRICS MECHANISM FOR CARRYING OUT THATMETHOD Filed Aug. 25, 1938 Jaren/ar:

Patented oer. 22, 1940.

UNITED STATES METHOD THE FORMATION OF PREVENTING R LESSENING 0FLONGITUDINAL STRIPES IN LOOPED FABRICS AND MECH- ANISM FOR CARRYING OUTTHAT METH- Curt Scheller, Chemnitz, Germany Application August 23, InGermany 1938, Serial No. 226,346 July 29, 1937 Claims. (CL 66-98) Thepresent invention relates to knitting. machines and is particularlydirected to an improvement devised to prevent or, at least, lessen theformation of disorderly stripes or ribs in the 5 looped fabricsmanufactured on flat knitting machines operating with spring needles.

It is a well known fact that knittedgoods produced on the aforementionedmachines are frequently provided with unsightly longitudinal stripes,which sometimes are called needle or sinker stripes. The cause of thesestripes is by no means a secret. They are principally due to the factthat the hooks of the spring needles, which are used in the machines inconsiderable numbers, are not always exactly alike. Slight variationsoccur, or in their curved shape or degree of elasticity, and willsufllce to cause the formation of the disorderly stripes. It is notsufilcient that all of the a other series of elements, which in thesinking and dividing section of a flat knitting machine of the ,type inwhich the loops of a row of loops are formed by one thread cooperate informing the loops, such as the sinkers, knock-over bits,

jacks and frame needles, are perfectly uniform in size and dimensions.will not insure the formation of uniform loops if through variations inthe height, curvature or elasticity of the hooks the size of some of theloops is varied at the expense of the size of adjacent loops as soon asthe hooks beginto open .after the pressure upon them has been released.It is obvious that a hook which is too high, too

' must necessarily produce the excess of material necessary for formingthe oversized loop will be pulled from adjacent loops formed on lower orless curved or less elastic hooks, with the result that theadiacentloops 0 will be correspondingly smaller in size. It is further obviousthat the same irregularity will recur in each row of loops at the samespot and therefore result in the formation .of the aforementionedunsightly longitudinal ribs or stripes. As long as the needle bars arenew the differences in the hooks will of course be insignificant, and

the stripes for that reason will be hardly noticeable. But after. a hilethe differences will be 60 more pronounced, partly because the constantwear on the needles has reduced the elasticity of some of the hooks morethan of others, and partly because of the new needles which had to besubstituted for those that had become outright der lective.

either in the height of the hooks Such uniformity alone In order toprevent the more or 1ess-unavoidable differences in the shape andelasticity of the hooks from interfering with the formation of univ formloops the applicant proposes to prolong the pressure on the hook andthereby retard its opening-up movement until a moment in which the hookis no longer able to influence through its opening-up movement the sizeof the loop formed on its'needle. This moment has arrived as soon as theloop has slipped over the top of the needle. 10 At this moment the loopsjust formed can no longer be influenced by any of the solid elements ofthe machine in such a manner that the size of some of the loops of therow could forciblybe changed with respect to'the size of other loops of15 the row.

' The prolongation of the pressure on the rock and retardation of theopening of the latter may be achieved in various ways. For a flatknitting machine of the type in which the loops of one row are formed byone thread (for instance a Cotton machine) thmapplicant proposes the useof a second presser member. According to the invention this secondpresser member has been arranged below the upper edge of the knock-oversinker, where it performs the function of pressing the hooks of a row ofneedles against their stems either at a time where the customarypressing action is still going on or immediately following 30 thatcustomary pressing action, for instance atthe moment when the loops justformed have slipped onto the hooks and the points of the hooks arebetween the knock-over sinkers. This additional pressing be of suchconstruction that the hooks are kept under pressure. until the loopshave left the tops of the needles. For this purpose the pressingmechanism should be a movable one and receive its driving impetus eitherfrom a special eccentric shaft or from the main shaft with the aid ofcams of known description.

Through the arrangement of the additional presser means the applicantobtains various im- 45 portant advantages.

The principal advantage is the fact that the formation of the disorderlyand unsightly longitudinal stripes or ribs is either completely pre-,vented or considerably lessened.

Another advantage resides in the feature, that the adjusting of theneedles done almost exclusively to prevent the formation of stripesandwhich always takes up considerable time, particularly in oldmachines, will no longer require 66 mechanism. should preferably 36 by apresser bar of that utmost care quently as before.

The third advantage is the logical consequent of advantage number two,since fewer and shorter and not be necessary as i'reproducing a moreperfect article with less effort, in a shorter time and at a reducedcost.

The invention is fully disclosed in the following description, of whichthe accompanying In the drawing- Figs. 1, 1a and 1b are views offrame-needles provided with different types of hooks; v Fig. 2 is a viewof a portion of the machine showing how the hook of the needle is closedknown construction, with one point of the hook;

Fig. 3 is a detail view showing the presser bar the additionalpressermember at the end of its jack sinker activity.

Referring more particularly to the drawing the numerals i, I, I" (Figs1, 1a and 11)) represent frame needles provided with various types. ofhooks 2, 2', 2", of which hook 2 is normally bent, while hook 2' isunusually outwardly curved and hook 2" of a somewhat flattenedformation. Mounted on the main shaft 3 (Fig. 2) of the 6 which atperiodical intervals acts upon a roller mounted on a lever arm 1 of thedouble-armed lever 1, 1, pivoted at i3. Lever arm I is spring-controlledby spring 5 and, owing to the action of cam 4 upon roller ii, is forcedagainst the tension of spring 5 in the direction indicated by the arrowA, while lever arm I is simultaneously swung in the opposite direction.The lever arm 1 is formed of thin metal plates or fingers, Of which eachone extends with .its free end 7" into the space between two knockoversinkers 8 just in front of a needle i. illustrates the Fig. 2

thereby enclosing the loop ii just formed by the III, while the loop I2previously formed and already added tothe fabric i2 encircles the stemof the needle Just below the point of the hook, owing to the upwardmovement of the needle. When the needle mounted in needle frame l5 movesdown through the encircling loop l2' the latter slips onto the back ofhook 2 while bar 9 recedes as illustrated in Fig. 3. This is the momentwhere the lever arm or finger 1' which has been inactive until nowperforms its function as a second presser element of the machine.Actuated by cam 4 the finger until the jack sinker i has receded to apoint where knocking over of the loops l2 and, hence, the formation of anew row of stitches can take place (Fig.

What I claim is:

1. In a knitting machine of the character deframe;

tween two of said knock-over sinkers in front of a needle; and a cam forimparting rocking motion to said double-armed lever.

2. In a flat knitting machine, sprin --needles for forming the loops;presser members or pressfiuenced in size by the the needle hooks.

3. In a knitting machine, spring needles for forming the loops; pressermembers theneedle hooks against the needle movement of the needle hooks.

5. The method of preventing the formation of unsightly longitudinalstripes caused by differently sized loops in looped fabrics produced onfiat knitting machines, particularly of the Cotton type, which consistsCURT SCHELLER.

